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Astro Bob: How to see Comet Tsuchinshan-ATLAS at dusk – Duluth News Tribune
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Astro Bob: How to see Comet Tsuchinshan-ATLAS at dusk – Duluth News Tribune

The comet is back! Many of you had trouble finding it in the morning sky last month because it was so close to the horizon. The thick air and haze absorbed much of the comet’s light, making it nearly impossible to spot. Observers much further south had an easier time because it was higher in the sky.

I followed the fuzzball on six mornings and never saw it with the naked eye, only through the camera viewfinder and once with binoculars. Fortunately, the evening performance of Tsuchinshan-ATLAS will be more accessible, although perhaps not as bright as expected, partly due to moonlight interference.

I finished on October 11 when the comet first entered the evening sky. Conditions were very good with clear skies and only a few cirrus clouds in the distance. I placed Venus in the southwestern sky and measured 2 1/2 fists to its right. After several attempts, I was able to spot the comet with my camera and then with 10×50 binoculars at 7:10 PM, 40 minutes after sunset. It was weak! But as the twilight deepened it became easier to see; my binoculars even showed a short tail. I tried my best to make out the comet with the naked eye, but couldn’t convince myself that I had seen it.

Although Tsuchinshan-ATLAS is much fainter than Venus, the brilliant planet will help point you there. Until about October 19, the comet will remain about 2 1/2 fists away from Venus, even as its angle with the planet gradually increases.

Don’t worry too much if the comet looks dim at this point, both visually and in photos. It is still low and strongly influenced by the twilight glow and haze. Things will improve soon.

Comet C/2023 A3 card better

This map shows the comet’s nighttime position through much of October as it gradually climbs the evening sky and becomes more visible.

Contributed / Stellarium with additions by Bob King

From the map you can see that the comet will quickly climb across the western sky over the coming nights. If you look at the same time every night, you will see the altitude steadily increasing. That’s a good thing! It means less air and dust to filter out that long, delicate tail. On October 14, the comet will set for about 40 minutes after the end of evening twilight in a dark sky. In the following nights the ‘window’ of darkness becomes longer and longer.

For that reason, you would expect the view of the comet to improve over time. And they will. But as altitude increases, Tsuchinshan-ATLAS also slowly fades away as its distance from Earth increases. It’s heading back into the “wilderness” of the solar system, far beyond the orbit of Pluto. There’s even a chance it could escape the sun altogether and blaze a trail into interstellar space.

We also have another problem: the moon. It is currently in the waxing moon phase and will be full on October 17. Its light will dilute the comet’s brilliance and “shorten” its apparent tail length from about October 15 through October 20. After that we are clear!

On the 20th, Tsuchinshan-ATLAS should be about third magnitude, with a nice, long tail easily visible to the naked eye from a dark, rural sky. If you live in the suburbs, you’ll need binoculars to see it clearly. But wherever you observe, binoculars will help you reveal the full extent of the tail, as well as any textures or colors the comet may exhibit. If you have a telescope, bring it along for close-ups of the beautiful nuclear region located in the comet’s head.

Anti-tail

Watch for the formation of a rare anti-tail beneath the comet’s head on October 14 and 15, from material it previously deposited along its orbit.

Contributed / Stellarium with additions by Bob King

Pay special attention to the comet on the evenings of October 14 and 15. Then we should see a prominent anti-tail sticking right under the head. This delicate light peak occurs when we view the comet’s orbit from the side. The dust deposited along its path over the past few months builds up and briefly glows as a secondary tail from our perspective.

Comet on smartphone

Even a cell phone can record the comet. This photo was taken on October 11 with an iPhone 14 Pro Max with exposures of 3 to 10 seconds.

Contributed / Ben Schurman

And don’t forget your phone. It should not be a problem to photograph Comet Tsuchinshan-ATLAS at dusk with a regular smartphone. Just hold it up, tap the comet to focus, then tap again to capture an image. A portable phone typically has an exposure time of 3 to 10 seconds, but if you purchase a phone bracket and mount it on a tripod, exposures of up to 30 seconds are possible.

I will continue to post new photos and updates about the comet on my Facebook page at facebook.com/astrobobking. Clear skies and happy hunting!

Bob King

“Astro” Bob King is a freelance writer and retired photographer for the Duluth News Tribune. You can reach him at [email protected].